The impact of valve surgery on short- and long-term mortality in left-sided infective endocarditis: do differences in methodological approaches explain previous conflicting results?

Aims The aim of this study was to evaluate the effect of valve surgery (VS) in infective endocarditis (IE) on 5-year mortality and to evaluate whether conflicting results reported by previous studies could be due to differences in their methodological approaches. Methods and results Four hundred and forty-nine patients with a definite left-sided IE were selected from a prospective, population-based study. Association between VS and 5-year mortality was examined with a Cox model. To determine the impact of different methodological approaches, we also analysed the relationship between VS and mortality in our database, according to each method used in the five previous studies. Valve surgery was performed in 240 patients (53%). It was associated with an increase in short-term mortality [within the first 14 post-operative days; adjusted hazard ratio (HR), 3.69; 95% confidence interval (CI), 2.17-6.25; P < 0.0001] and a decrease in long-term mortality (adjusted HR, 0.55; 95% CI, 0.35-0.87; P = 0.01). At least 188 days of follow-up were required for VS to provide an overall survival advantage. When applying each study's method to our database, we obtained results similar to those reported. Conclusion Previous conflicting results appear to be related to differences in statistical methods. When using appropriate models, we found that VS was significantly associated with reduced long-term mortality.